This invention concerns energy storage devices such as are used in regenerative braking systems for storing and releasing the energy normally dissipated in the braking of vehicles so that this energy may be utilized in vehicle propulsion.
This invention is specifically concerned with providing an elastomeric member and device such as may be usable in energy regenerative systems utilizing a torsionally stressed elongated elastomeric member.
The present invention is related to inventions described in U.S. Pat. Nos. 4,246,988; 4,305,489; 4,310,079; 4,319,655; 4,333,553, describing regenerative braking systems.
In these patents, a regenerative braking system and energy storage device is disclosed including such an elongated elastomeric member which is torsionally stressed in order to absorb braking energy. As described in U.S. Pat. No. 4,333,553, it is advantageous to axially prestress the elastomeric member since the member has a tendency to knot at predetermined torsional stress levels, and the tendency to form a knot is decreased by applying an axial or stretching tension on the elastomeric member.
The knotting tendency is a disadvantage since the fatigue life of the elastomeric member is greatly affected by knotting during the stressing cycles.
It is desirable to enclose such an elastomeric member by mounting it within a confining housing in order to protect the member from the environment, and to provide a safety shield.
The axial prestressing is achieved by stretching and results in a very substantial difference in diameter of the elastomeric member in its relaxed and stretched conditions.
In the interest of conserving space, it is desirable that the housing be of a diameter no larger than is necessary to receive the elastomeric member in its stretched condition.
It is also highly desirable that a sure and reliable mechanical connection to the ends of the elastomeric member be provided while allowing a constant diameter assembly.